温度对大海马摄食行为及生长速率的影响

选取体质良好、活力强的大海马(Hippocampus kuda Bleeker),体重(3.075 g±0.16 g)、体全长(11.55 cm±0.31cm)。设置18℃、23℃、28 3℃个实验组和1个对照组(CT组:自然变温),每组3个重复,实验周期28 d。结果显示,大海马在23℃时生长速率最快,摄食活跃;28℃大海马反应最迅速(5.8 s±0.74 s),摄食量最大(153.92 g±10.33 g),活动频繁,泳速大;而18℃和自然变温条件下对食物的反应不敏感,多缠绕在附着物上,摄食时呈聚集式分布;23℃和28℃时,相对活跃,会主动游向饵料摄食,摄食效率较高。综上所述,温度的改变对大海马的生长速率及摄食行为均有一定影响;在适宜温度下,大海马的活力大,摄食量多,生长速率相对较快。本研究旨在为大海马饵料开发和养殖环境优化提供科学数据。     

Live prey first feeding regimes for short‐snouted seahorse Hippocampus hippocampus (Linnaeus, 1758) juveniles

As with many species of seahorses, Hippocampus hippocampus wild populations are being subjected to uncontrolled exploitation in their natural environment. Thus, aquaculture could contribute to satisfy the commercial demand for animals while promoting the recovery of wild stocks. The present study was conducted to compare the effect of the substituting Artemia nauplii with rotifers for first feeding seahorse juveniles. Survival, growth and biochemical composition of prey organisms and fish were studied during the feeding trial. In addition, to help the biometric study, an anaesthetic test was also carried out using clove oil. The results showed excellent survival (average 60%) in juveniles exclusively fed with Artemia, with better values than those reported previously obtained by other authors for this species. By comparison, high mortality and poor growth were observed during first feeding with seahorses fed on rotifers. This could have been related to the lower energy intake and poorer nutritional value of the rotifers. Furthermore, clove oil concentrations of 25 ppm were found to work well as an anaesthetic for seahorse juveniles. Overall, first feeding Artemia alone was found to be an efficient and simplified method for feeding young H. hippocampus fry, building the principles for their culture for ornamental or re‐stocking purposes.     

Rearing the spotted seahorse Hippocampus kuda by feeding live and frozen copepods collected from shrimp ponds

This study evaluated the use of live and frozen copepods collected from shrimp ponds for rearing juveniles of the spotted seahorse Hippocampus kuda. Protein and HUFA contents in frozen copepods were all higher than in Artemia nauplii, the conventional live food for seahorse juveniles. The results of this study showed that copepods can be used as feed for rearing seahorse fry and juvenile. The spotted seahorse showed obvious preference for live copepods and rarely fed on dead copepods on the tank bottom. Furthermore, the combination of frozen copepods and live Artemia nauplii resulted in highest growth and highest survival of the experimental seahorses. Further research on possible effects of DHA:EPA ratio on survival and growth of young H. kuda is recommended.     

Feeding selectivity of the seahorse,Hippocampus kuda (Bleeker), juveniles under laboratory conditions

This study examined the feeding selectivity of Hippocampus kuda juveniles under captive conditions and evaluates different food organisms that could be used to improve hatchery‐rearing of this species. Newly born H. kuda were reared for 10 days in 60‐L capacity tanks and fed rotifers (Brachionus rotundiformis), zooplankton (mostly Pseudodiaptomus annandalei and Acartia tsuensis) alone or both food sources. The size and amount of food ingested increased as seahorses grew. Selective feeding of seahorses appeared to change as they develop, preferring copepod adults over nauplii and rotifers. A. tsuensis was highly selected by juveniles over P. annandalei. Specific growth rate in terms of body weight (SGR‐BW, 15% day^–1) was the highest and mortality rate (9% at day 10) the lowest in seahorses fed a mixed food sources. Slowest growth rate (0.3% day^–1) and highest mortality rate (60% at day 7) were observed in seahorses fed rotifers alone. These results indicate that copepods are suitable food for seahorse juveniles, but a mixture of food organisms in the rearing tank environment enhances survivorship and growth of H. kuda, thus potentially providing a source of cultured rather than wild specimens for characterizing the life history of this threatened species.     

Ontogeny of digestive enzymatic capacities in juvenile seahorses Hippocampus guttulatus fed on different live diets

Differences in survival and growth rates in seahorse Hippocampus guttulatus juveniles feeding on Artemia sp. or copepods have been related to specific digestive capacities of seahorse newborn, which are capable of actively forage on available prey from the first day of live. Other seahorse species, such as H. abdominalis and H. hippocampus, show high success feeding on Artemia nauplii suggesting species-specific differences in the digestibility of prey among seahorses. In this study, the profiles of digestive enzyme activity during the initial 15 days after release (DAR) were very low for trypsin, chitinase and α-amylase. In contrast, higher activities towards any of the assayed substrates for lipase (butyrate, octanoate and oleate) were evident from 0 DAR onwards. From 15 DAR onwards, the effect of diet composition became evident in juveniles previously fed on a mixed diet (Artemia + copepods), which showed a clear increase in all the assayed enzymes when compared with juveniles fed on Artemia as a sole prey. As a practical applicability of this study, a feeding schedule ensuring an adequate digestibility of the prey is proposed based on ontogenetic enzymatic activities of seahorse juveniles fed on different prey.     

大海马在人工养殖条件下的生长速率

报道了在人工养殖条件下,大海马(Hippocampus kuda Bleeker)的体长与体重的相对生长率、生长比率及生长速度与饵料、水温等环境因子的关系。结果表明，大海马生长高峰期为5～11月，群体体长月平均增长率为12.20％，体长特定增长率为15.92％；体重月平均增重率为15.87％，体重特定增重率为27.70％，群体增重倍数为13.8。大海马体长呈逻辑斯蒂曲线增长，关系式为L＝192.3460／(1＋e     

Breeding and juvenile culture of the lined seahorse, Hippocampus erectus Perry, 1810

All seahorse species worldwide have been placed under CITES Appendix II since 2004, because they have been over-exploited for traditional Chinese medicine and aquarium trades. Aquaculture has been recognized as a long-term solution for sustaining the seahorse trade while minimizing wild collection. In this study, we evaluated the breeding and juvenile culture of an important aquarium seahorse species, the lined seahorse Hippocampus erectus, Perry 1810. Pairing, mating and copulation behavior were observed. Gestation time and brood size were 17.33 ± 2.94 days and 272.33 ± 66.45 individuals/brood, respectively. Growth rates differed among juveniles from different broods. Effects of temperature on the growth rates and survivorship of the juveniles during the first two weeks were compared. The highest growth rate and survivorship of the juveniles occurred at 28–29 °C among the temperatures tested (24–33 °C). Growth rate and survivorship of the juveniles during the first 9 weeks at 28 °C were investigated. The final standard length and survivorship of the juveniles were 6.32 ± 0.52 cm and 71.11 ± 10.18%, respectively, and the relationship between the wet weight and the standard length of the juvenile seahorses can be expressed as: W = 0.0034 L^2.5535 (r² = 0.9903, n = 12, P < 0.01). These findings suggest that H. erectus is a good candidate for commercial aquaculture.     

Biochemical composition of the wild and cultured seahorses, Hippocampus kuda Bleeker and Hippocampus trimaculatus Leach

The biochemical composition of wild and cultured seahorses Hippocampus kuda Bleeker and Hippocampus trimaculatus Leach was analysed in this study. The crude protein contents (% dry weight) of wild seahorses were high: 72.7±2.5% in H. kuda and 78.5±4.2% in H. trimaculatus . The crude lipid contents (% dry weight) of wild and cultured seahorses (1.1±0.1 vs. 1.4±0.2 for H. kuda and 1.2±0.1 vs. 1.2±0.2 for H. trimaculatus ) were low and did not differ significantly ( F _3, 12=1.461, P =0.12). The essential amino acids and flavour-enhancing amino acids in wild seahorses were higher than those in cultured seahorses, although the essential amino acid index in wild and cultured H. kuda and H. trimaculatus were generally low. The total amino acid content decreased with growth in cultured H. trimaculatus ( F _3, 12=14.927, P <0.05). The poly-unsaturated fatty acid (PUFA) contents in wild and cultured H. kuda and H. trimaculatus were 21.69%, 37.72%, 21.39% and 33.89% respectively. The fatty acid content in seahorses first decreased and then increased with growth both in wild and in cultured H. trimaculatus . The PUFA/saturated fatty acid ratio was 1.31 in cultured H. kuda and 0.87 in cultured H. trimaculatus . The trace metal concentrations in the wild seahorses were relatively low. The results presented in this study provide biochemical information necessary for understanding the medicinal value of H. kuda and H. trimaculatus and for elucidating the potential dietary requirements for their culture.     

Growth,Survivorship, Air‐bubble Disease,and Attachment of Feeble Juvenile Seahorses,Hippocampus kuda (Bleeker, 1852)

Seahorse aquaculture has been a focus for meeting the demand of traditional medicine and aquarium. Feeble (poor quality) juveniles are commonly found in the commercial seahorse culture. In this study, we compared the growth and survival performances of the feeble and healthy common seahorses Hippocampus kuda. The results show that the feeble juveniles had high growth and survival at the temperature of 27–29 C and salinity of 26–28‰ with frequent feeding (≥three times a day) during first 5 wk. Through a 12‐wk investigation, we found that the air‐bubble disease could significantly affect the specific growth rate and survival of the feeble juveniles. There was a positive and significant correlation between the substrate‐attachment rate and survival rate in the feeble juveniles, and substrate‐attachment rate may be used to assess the quality of the feeble populations in the seahorse H. kuda.     

海马网箱养殖试验

本文报道海马网箱养殖试验。海马可以进行网箱养殖，需要选择合适的养殖水环境，改进网箱设置，采用适当的饵料和投喂方式，防治病害，提高成活率。     

Use of Artemia supplemented with exogenous digestive enzymes as sole live food increased survival and growth during the larviculture of the longsnout seahorse Hippocampus reidi

This study evaluated the effect of exogenous digestive enzymes on the survival, growth performance and morphology of the digestive tract of juveniles of the longsnout seahorse Hippocampus reidi fed exclusively with Artemia and supplemented with five different concentrations of porcine pancreatin (PP) (0, 5, 25, 50 and 75 mg/L from birth until 30 days after release). The results found in the present study clearly show that there was a significant increase in survival and growth as well as substantial changes in the morphology of intestinal villi in seahorses fed exclusively with Artemia supplemented with 75 mg/L PP. Therefore, the use of digestive enzyme supplementation constitutes an important advance for the establishment of a more efficient and practical feeding protocol (exclusive use of Artemia) for juveniles of the longsnout seahorse.     

Study on an integrated eco‐aquaculture system for rearing the yellow seahorse,Hippocampus kuda Bleeker

Seahorse aquaculture is challenged by insufficient feeding supply and lack of biological and nutritional knowledge, resulting in low survival rate and poor economical profitability. We report here an integrated eco‐aquaculture system in which the yellow seahorse and its natural prey were co‐cultured with fertilized water and seaweed in cement ponds. In the first stage, urea (10 g m^?3) and chicken manure (50 g m^?3) were used to fertilize the cultured water, 5–7 days later, rotifer and micro‐crustaceans were flourishing. Then, seahorse juveniles were stocked at 200 ind m^?3. After 2 weeks, seaweed Gracilaria lichevoides was transplanted into the ponds to regulate water quality, light and to provide holdfast attachment for seahorses. The optimal density of G. lichevoides was controlled between 0.5 and 2 kg m^?3. The introduction of seaweed provides the habitat for natural food of seahorse. Within the cluster of the seaweed, small crustacean density was over 450 individuals per 100 g of fresh weight. Initial size of seahorse juvenile was 1.03 ± 0.091 cm, After the 146‐day rearing period, seahorse survival rates were 70.8%, 57.7% and 42.5%, and body standard lengths were 11.33 cm, 10.84 cm and 10.04 cm in the integrated eco‐aquaculture system (GFA) and in monoculture systems of FA (fertilized + feeding) and BA (only feeding) respectively. This system incorporated traditional Chinese aquaculture technique in which feedings nature food organisms were cultivated by fertilization and ecological regulation. Results from these preliminary experiments suggest that the integrated system could be technically feasible, suitable and exemplary.     

Effect of Different Live Prey on Spawning Quality of Short‐Snouted Seahorse,Hippocampus hippocampus (Linnaeus, 1758)

The importance of a suitable diet for reproduction has been recognized as one of the major factors in ornamental aquaculture. In seahorses, mysids have been described as preys in the wild. Also, Artemia has been usually employed for rearing fish, including syngnathids. Therefore, the aim of this work was to evaluate the effect of these live preys on the spawning quality of Hippocampus hippocampus. After 108 d, no differences were found in adults concerning all biological parameters evaluated, but broodstock fed on mysids showed better results than Artemia regarding number of spawning events (12 vs. 3), brood sizes (233.50 ± 59.04 vs. 68.00 ± 57.97 juveniles), and newborn seahorses standard length (10.61 ± 0.64 vs. 8.75 ± 1.32 mm). The better nutritional quality of mysids, overall in Docosahexanoic acid, could be one of the main responsible factors. However, mysids stock is conditioned by natural catches and rearing techniques are little known. Another alternative would be to combine them with Artemia in mixed diet. Further research must be done concerning mysids breeding techniques to delineate their employment as a sustainable prey for seahorse aquaculture. This trial showed for the first time the effect of mysids to enhance reproduction efficiency in H. hippocampus.     

The effect of diet on ontogenic development of the digestive tract in juvenile reared long snout seahorse Hippocampus guttulatus

Ontogenetic development of the digestive tract and associated organs in long snout seahorse Hippocampus guttulatus juveniles was morphologically and histologically examined from the time of release from the male’s pouch until 72 h after the first meal. When released from the male’s pouch, juvenile seahorses are small adult replicates. This means that unlike other teleost fish larvae, the first developmental phase has already taken place, and juveniles are morphologically prepared and able to feed on live prey immediately following parturition. At this stage, the buccopharynx, oesophagus, and intestine already appear to be fully developed. The intestine is divided into the midgut and hindgut by an intestinal valve, and intestinal villi are visible in the midgut. When fed with DHA-Selco^® enriched Artemia, H. guttulatus juveniles developed a severe condition of overinflation of the gas bladder. The continuous overinflation of the gas bladder forced air into the gut (48 h after the first meal), resulting in overinflation of both the gut and the gas bladder (72 h after the first meal), and death occurred within 120 h after the first meal. When fed natural copepods, H. guttulatus juveniles continued a normal feeding activity with no signs of intestinal disorders, and the gas bladder and intestine maintained their normal shape. This is the first study to positively associate gas bladder overinflation of juvenile seahorses with nutritionally unbalanced diets, and not to gas supersaturation alone. It is therefore necessary to develop more adequate feed and/or enrichment products to improve the survival of juvenile seahorses in captivity.     

池养大海马的摄食_生长和生态转换效率

对大海马 (平均体长 92 .82± 2 .0 5 2 6mm ,平均体重 6 .6 9± 0 .4 5 70g)在养殖条件下 (放养密度为 2 0 0ind·m-3 ,溶解氧保持在 5 .5mg·L-1以上 ,生物耗氧量低于 3mg·L-1,pH值 7.5～ 8.2 ,透明度 5 0～ 85cm ,盐度 15 .2～ 2 6 .5 )的摄食、生长和食物生态转换效率进行了定量研究。通过系统取样 ,测量海马的全长、体重和消化道内食物重量 ,计算其增长速度、摄食率、消化道排空率、生态转换效率等数值 ,发现大海马的摄食每天有两个摄食高峰 ,即 12 :0 0和 18:0 0 ,晚上不摄食或很少摄食。大海马的日摄食量为 16 .6 342± 0 .782 0g·(10 0g) -1,日摄食率为 1177.2 5cal·ind-1,排空率 0 .14 4 4g·(10 0g) -1·h-1,食物转换效率 2 0 .0 4 % ,能量转换效率 31.4 2 %。体长日平均增长速度和日均增长率分别为 1.176 6mm和 1.2 7% ;体重日平均增重速度和日均增重率分别为0 .182 0g和 2 .2 7%。通过多元回归分析建立摄食率与体重及温度的相关关系 ,得出下列关系式 :C =6 .75 4 4+0 .30 14T +0 .2 190W (F =83.5 96 3,F0 .0 1=18.0 0 ,F >F0 .0 1)。     

Experiments in rearing rabbitfish (Siganus rivulatus) in sea water

The initial experiments in rearing rabbitfish (Siganus rivulatus) in sea water indicate that this fish may be suitable for commercial cultivation. Juveniles are available in large numbers during summer and fall along the Mediterranean and Red Sea coast of Israel. Juveniles collected in Eilat (Red Sea) were kept in tanks and submerged cages and fed fish pellets. After 29 days in tanks, the first group of fish which averaged 0.91 g upon capture increased in weight to an average of 3.7 g. A subsequent school of juveniles kept in sea cages for 84 days increased in weight from an average of 7.3 g to 28.5 g.     

Fisheries and trade of seahorses, Hippocampus spp., in southern India

Abstract  Seahorses ( Hippocampus spp. ) are a major commodity fished from the shallow coastal seas of the south coast of India where there is an abundance of sea grasses, sponges and corals. They are in great demand for export as traditional medicines, curios and aquarium fish. Organised fishing and trade of seahorses exists in India along the Palk Bay and Gulf of Mannar coasts. At the Palk Bay coast, seahorses are targeted by divers along with sea cucumbers ( Holothuria spp. ) and gastropods (e.g. Murex spp., Xancus pyrum Hornell). In the Gulf of Mannar, most of the seahorses are landed as bycatch of shrimp trawling. Seahorses are also fished from Kerala as a bycatch of trawling, although no organised fishery and trade exists. Five species of seahorses were identified from the Palk Bay coast, whereas only two species were obtained from Kerala. Most seahorses from India are exported to Singapore, Hong Kong, Malaysia and the United Arab Emirates. The volume of dried seahorse trade from India was estimated to be 9.75 t as derived from catch data in 2001, which was much higher than official statistics of 4.34 t during 2001–2002, suggesting the major part of the exports might be through non-conventional means and goes undeclared. Some aspects of the impact of large-scale fishing and trade on conservation of these seahorses are discussed.     

Long-term effects of dietary fat level and feeding rate on growth, feed utilization and carcass quality of Atlantic salmon

Two extruded diets designed to have fat levels of 220 g kg⁻¹ (F22) and 300 g kg⁻¹ (F30) were fed to Atlantic salmon Salmo salar L. in two different experiments during the sea rearing period (from 0.2–0.3 kg to 3–4 kg). Each diet was fed restricted and isoenergetically at two feeding rates to fish in triplicate groups. In one of the experiments, a supplementary group of fish was fed to satiation with the F30 diet. All fish were slaughtered and evaluated for quality according to a commercial standard.
No difference in growth was observed between fish fed the two diets at similar feeding rates and the growth was proportional to the amount of dietary energy offered. Feed conversion ratios decreased according to higher energy content in the F30 diet, and the nitrogen and phosphorus retention increased significantly. Fish fed the F30 diet revealed a higher incidence of sexual maturity. Fat content in cutlets and dressed carcasses were significantly affected by feeding rate but not by dietary fat level. Fish fed the F30 diet had more visceral fat and, consequently, lower dress-out percentage. Mortality, liver size and liver colour were not significantly affected by dietary fat level.
These experiments showed that even large differences in dietary fat level employed for the entire sea rearing period of Atlantic salmon, did not, or only marginally affected the cutlet and dressed carcass fat content. The high fat diet improved the feed utilization, thus decreasing the discharge to the environments. Furthermore, it resulted in greater growth at ad libitum feeding.     

Biochemical Composition of Six Seahorse Species, Hippocampus sp., from the Chinese Coast

The biochemical composition of six seahorse species from the Chinese coast was analyzed in this study. The crude protein content (% dry weight) of Hippocampus kuda, Hippocampus trimaculatus, Hippocampus kelloggi, Hippocampus spinosissimus, Hippocampus histrix, and Hippocampus comes was 70.70 ± 2.12%, 77.59 ± 1.06%, 78.31 ± 1.74%, 71.15 ± 1.32%, 68.07 ± 1.96%, and 76.59 ± 3.25%, respectively. The major amino acids (>5% of the total) in seahorses were arginine, aspartic acid, glutamic acid, alanine, and glycine, and there were significant differences in essential amino acids (EAA) (as % of total protein) among the six species (P < 0.05). The scores of EAA were balanced in the seahorse species, and the essential amino acid indexes of the six species were 41.63, 40.89, 44.84, 39.60, 39.31 and 45.45, respectively. The content of flavor‐enhancing amino acids of the six seahorse species was generally high, ranging from 28.16 ± 1.12% in H. histrix to 32.90 ± 2.17% in H. kelloggi (P < 0.05). The total lipid content was generally low, ranging from 0.96 ± 0.08% in H. histrix to 2.02 ± 0.24% in H. comes. The most abundant fatty acid was C16:0, ranging from 15.04 ± 0.67% in H. trimaculatus to 31.04 ± 4.32% in H. spinosissimus. The combination of eicosapentaenoic acid and docosahexaenoic acid as the fraction of the total fatty acids was high (0.14–0.35). The polyunsaturated fatty acid/saturated fatty acid ratio ranged from 0.40 in H. kuda to 1.19 in H. histrix. The trace metal concentrations in the seahorses were generally low. The six seahorse species examined provide a food source for humans with low fat, high protein, good levels of EAA, and high beneficial trace elements. These results are valuable in developing diets for culturing seahorse species.     

The Effects of Different Feed Enrichments on Survivorship and Growth of Early Juvenile Longsnout Seahorse,Hippocampus reidi

Culturing the longsnout seahorse, Hippocampus reidi, remains challenging because unlike most cultured seahorse species, Artemia is not an optimal first feed. Ideally, more nutritious live feeds such as wild plankton or copepods should be used, but are not always readily available. Therefore, facilities commonly utilize enriched rotifers. Numerous feed enrichment products exist, including Dan's Feed Artemia Enrichment^®, (Dan's Feed) which is a blend of commercially available enrichment products. The aim of this study was to assess the survivorship, growth, and condition factor (CF) of 0–28 DPR (days post release) H. reidi fed with rotifers and Artemia enriched with Dan's Feed. This enrichment was evaluated against (1) rotifers and Artemia enriched with live alga (Isochrysis galbana), and (2) wild plankton and Artemia enriched with Dan's Feed. At 28 DPR, in terms of survivorship and growth, seahorses fed with rotifers and Artemia enriched with Dan's Feed had a lower CF and outperformed those fed rotifers and Artemia enriched with I. galbana. Seahorses fed with rotifers and Artemia enriched with Dan's Feed performed on par with those fed with wild plankton and Artemia with no significant difference in CF. These findings demonstrated that the culture of H. reidi may be feasible with rotifers and Artemia enriched with Dan's Feed .